【编程题】二分查找

void BinarySearch(int a[],int n,int key) {
	int left = 0, right = n-1;   //初始化左右
	while (left<=right) {
		int mid = (left + right) / 2;  //二分查找的下标
		if (a[mid] > key)right = mid-1;
		else if (a[mid] < key)left = mid+1;
		else {
			cout<<"position==="<< mid<<endl;
			return;
		}
	}
	cout<<"查找失败！"<<endl;
}